Seal mechanism, valve, and rotary joint

Abstract

A seal mechanism (10) is provided with: a shaft (21) having an axial part (24), a large-diameter part (25) having a larger diameter than the axial part (24), and a circular lid (26) provided on one end of the large-diameter part (25) and a peripheral surface of the axial part (24); a spring (22) disposed at the other end of the large-diameter part (25); an elastic body (23) placed on a recess (first recess (27)) formed on a peripheral surface of the large-diameter part (25); and an outer cylinder portion (30) that encloses the shaft (21), the spring (22), and the elastic body (23), has a tapered part (31) formed along a curved surface of the circular lid (26), and is in contact with at least the large-diameter part (25) and the circular lid (26) of the shaft (21).

Description

Seals, valves and rotary joints

[0001] The present disclosure relates to a sealing mechanism, a valve, and a rotary joint.

[0002] Various valves for controlling the flow of fluid in piping have been known. For example, the technology of Japanese Utility Model Publication No. 01-116287 (JP.H01116287.U) discloses a stem seal device that is particularly applicable to ball valves that are opened and closed by the rotation of a valve element caused by operating a handle.

[0003] The ball valve in JP.H01116287.U requires a large number of parts to fill a relatively large space with various components. In addition, the sealing function is expected to be achieved by the elastic deformation of the packing material, so the design must take elastic deformation into account, and the design of manufacturing tolerances becomes complicated.

[0004] The present disclosure has been made in consideration of these points, and aims to provide a sealing mechanism, a valve, and a rotary joint that can provide a sealing function with a simple configuration.

[0005] The sealing mechanism of the present disclosure comprises: a shaft portion having a shaft portion, a large diameter portion larger in diameter than the shaft portion, and a dome portion provided on one end of the large diameter portion and on the circumferential surface of the shaft portion; a spring portion disposed at the other end of the large diameter portion; an elastic body placed in a recess formed on the circumferential surface of the large diameter portion; and an outer tube portion that encompasses the shaft portion, the spring portion, and the elastic body, has a tapered portion formed along the curved surface of the dome portion, and is in contact with at least the large diameter portion and the dome portion of the shaft portion.

[0006] In the sealing mechanism of the present disclosure, the taper angle of the tapered portion may be an angle in the range of 30° or more and less than 180°.

[0007] The sealing mechanism of the present disclosure may include a bearing placed on the spring portion, and a fixing member that fixes the bearing.

[0008] In the seal mechanism of the present disclosure, the elastic body may be an O-ring.

[0009] In the seal mechanism of the present disclosure, the other end surface of the large diameter portion may extend in a radial direction relative to the longitudinal axis of the shaft portion.

[0010] In the sealing mechanism of the present disclosure, the inner circumferential surface of the outer cylindrical portion may be in contact with the elastic body.

[0011] The valve of the present disclosure includes the above-described sealing mechanism.

[0012] The rotary joint of the present disclosure includes the above-described sealing mechanism.

[0013] 1 is a schematic diagram showing the configuration of a valve according to the present embodiment; FIG. 2 is a diagram showing a modified example of the present embodiment, and is a schematic diagram showing the configuration of a rotary joint including the seal mechanism according to the present embodiment;

[0014] A seal mechanism 10 and a valve 1 according to the present embodiment will be described below with reference to the drawings. Figures 1 and 2 are views showing the seal mechanism 10 and the valve 1 according to the present embodiment. Of these, Figure 1 is a schematic diagram showing the configuration of the valve 1 according to the present embodiment. Figure 2 is a view showing a modified example of the present embodiment, and is a schematic diagram showing the configuration of a rotary joint 100 including the seal mechanism 10 according to the present embodiment.

[0015] First, a seal mechanism 10 according to the present embodiment will be described. As shown in Figure 1, the seal mechanism 10 according to the present embodiment includes a stem 20 including a shaft portion 21, and an outer cylindrical portion 30 that encloses the stem 20. In this specification, a ball valve will be used as an example of the valve 1.

[0016] The stem 20 comprises a shaft portion 21, a spring portion 22 that biases the ball 70, and an elastic body 23 attached to the circumferential surface of the shaft portion 21, and is a component that rotates the ball 70 by rotating around the axis.

[0017] The shaft portion 21 has a rod-shaped or cylindrical base shaft portion 24 having a longitudinal axis, a large diameter portion 25 having a larger diameter than the shaft portion 24 and constituting part of the shaft portion 24, and a hemispherical dome portion 26 extending from one end of the large diameter portion 25 toward the circumferential surface of the shaft portion 24.

[0018] The shaft 24 is a rod-shaped or cylindrical metal member. One end of the shaft 24 is connected to the ball 70, and transmits power to the ball 70 by rotation. The other end of the shaft 24 is connected to the handle 40, and the shaft 24 is rotated by rotating the handle 40 forward or backward.

[0019] The large diameter portion 25 is a portion of the shank 24 that has an expanded diameter and occupies a continuous area within the shank 24. The large diameter portion 25 extends from the center of the shank 24 toward one end. The diameter of the large diameter portion 25 can be in the range of 1.5 to 2.5 times the diameter of the shank 24. If the diameter of the large diameter portion 25 is less than 1.5 times the diameter of the shank 24, the hemispherical portion of the dome portion 26 will be relatively small, reducing its practicality in terms of manufacturing tolerances during commercialization. Furthermore, if the diameter of the large diameter portion 25 is more than 2.5 times the diameter of the shank 24, the product size may be too large for commercialization. The ratio of the longitudinal lengths of the large diameter portion 25 and the shank 24 can be in the range of 1:3 to 1:10 to ensure its functionality as a shaft.

[0020] A first recess 27 is formed on the circumferential surface of the large diameter portion 25. The first recess 27 is an endless depression formed in the circumferential direction of the circumferential surface of the large diameter portion 25. The ratio of the depth to the width of the first recess 27 can be in the range of 1:1.1 to 1:3, inclusive, from the viewpoint of not impairing the function of the housed elastic body 23.

[0021] Concave portion 26 is a hemispherical portion extending from one end of large diameter portion 25 toward the circumferential surface of shaft portion 24. Concave portion 26 and shaft portion 24 have central axes that overlap. The size of the hemispherical surface of concave portion 26 varies with a curvature that corresponds to the sizes of shaft portion 24 and large diameter portion 25.

[0022] The spring portion 22 is a mechanical element disposed at the other end of the large-diameter portion 25. For example, the spring portion 22 is a member placed on the other end surface of the large-diameter portion 25 or one or more members that can bias the other end via a member placed on the other end surface of the large-diameter portion 25, and is a member that can bias the outer tube portion 30. For example, a leaf spring is used as the spring portion 22. Furthermore, the length of the spring portion 22 disposed at the other end of the large-diameter portion 25 in a direction perpendicular to the biasing direction is equal to or less than the radial length of the other end surface of the large-diameter portion 25. When one spring portion 22 is used, the spring portion 22 is disposed along the circumferential surface of the other end of the large-diameter portion 25 to bias the outer tube portion 30 evenly. When multiple spring portions 22 are used, the spring portions 22 are disposed at equal intervals around the circumferential surface of the other end of the large-diameter portion 25 to bias the outer tube portion 30 evenly.

[0023] When the stem 20 is enclosed in the outer cylindrical portion 30, the spring portion 22 exerts a certain biasing force toward the contact point between the dome portion 26 and the tapered portion 31.

[0024] The other end surface of the large diameter portion 25 extends in a radial direction relative to the longitudinal axis of the shaft portion 21. In other words, the plane direction of the other end surface of the large diameter portion 25 is perpendicular to the biasing direction.

[0025] A bearing 50 is mounted on the spring portion 22. For example, a ball bearing is used as the bearing 50. The bearing 50 is mounted on the other end surface of the large diameter portion 25. A fixing member 60 is provided on the surface opposite to the mounting surface of the spring portion 22 and the bearing 50, to fix the bearing 50 within the stem 20, in order to limit movement of the spring portion 22 and the bearing 50 in the biasing direction.

[0026] The fixing member 60 is fixed to the circumferential surface of the outer tube portion 30 and is a member that limits movement in the biasing direction of the member disposed at the other end of the large diameter portion 25. The fixing member 60 also maintains the biasing force from the spring portion 22 on the contact points between the dome portion 26 and the tapered portion 31 when the shaft portion 21 is in a stationary state and before and after rotation. For example, a C-ring is used as the fixing member 60. A rod-shaped member 61 having a longitudinal axis is disposed near the fixing member 60.

[0027] The rod-shaped member 61 has a rod-shaped portion 62 that extends perpendicular to the longitudinal axis of the shaft portion 21. One end of the rod-shaped portion 62 is connected to the circumferential surface of the shaft portion 21, and the other end of the rod-shaped portion 62 is provided with a locking member 64. The locking member 64 is slidably fitted into a second recess 63 formed on the inner circumferential surface of the outer tube portion 30.

[0028] The elastic body 23 is a member placed in the first recess 27 formed on the circumferential surface of the large-diameter portion 25. For example, the elastic body 23 is made of one or more rubber materials. When one elastic body 23 is used, an O-ring is used and fitted into the first recess 27. When multiple elastic bodies 23 are used, the elastic bodies 23 have a spherical or rectangular parallelepiped shape and are arranged and filled in the first recess 27 without leaving any gaps between them to ensure sealing function. Furthermore, the diameter of the elastic body 23 is equal to or greater than the depth of the first recess 27. This allows for effective sealing function. Furthermore, the ratio of the diameter of the elastic body 23 to the width of the first recess 27 can be in the range of 1:1.1 to 1:5, inclusive, to prevent the sealing function of the housed elastic body 23 from being weakened.

[0029] The outer tube portion 30 is a metal member that encases the stem 20. The outer tube portion 30 encases the shaft portion 21, the spring portion 22, and the elastic body 23. The outer tube portion 30 also has a tapered portion 31 formed along the curved surface of the dome portion 26. The outer tube portion 30 also contacts at least the large-diameter portion 25 and the dome portion 26 of the shaft portion 21. As described above, the inner circumferential surface of the outer tube portion 30 is formed with a second recess 63 into which the locking member 64 provided at the other end of the rod-shaped portion 62 is fitted. The width of the second recess 63 is equal to or greater than the diameter of the locking member 64. The second recess 63 formed on the inner circumferential surface of the outer tube portion 30 is formed in a continuous ring shape on the inner circumferential surface of the outer tube portion 30.

[0030] As described above, the diameter of the elastic body 23 is equal to or greater than the depth of the first recess 27. Therefore, when the stem 20 is enclosed by the outer tubular portion 30, the inner circumferential surface of the outer tubular portion 30 contacts the elastic body 23.

[0031] The tapered portion 31 is a portion of the outer tube portion 30 that is disposed opposite the hemispherical curved portion of the dome portion 26 when the stem 20 is enclosed by the outer tube portion 30, and is formed in a tapered shape. Because the tapered portion 31 is formed in a tapered shape and the dome portion 26 has a hemispherical shape, a portion of the tapered portion 31 comes into contact with a portion of the hemispherical curved portion of the dome portion 26, so that the two are in line contact.

[0032] The taper angle (θ) of the tapered portion 31 is preferably 20° or more and less than 180°, and more preferably 30° or more and less than 180°, from the viewpoint of avoiding interference with smooth rotation due to components getting caught between each other when the shaft portion 21 rotates while still providing a sealing function.

[0033] Next, a valve 1 including the seal mechanism 10 according to this embodiment will be described. As shown in Figure 1, the valve 1 according to this embodiment includes the above-described seal mechanism 10, a ball 70 having a hole formed therein and connected to a stem 20, and a ball seat 71 that sandwiches the ball 70.

[0034] The ball 70 is a spherical member with a through hole formed therein and is connected to the stem 20. The stem 20 is connected to the surface of the ball 70 in a direction perpendicular to the opening direction of the through hole formed in the ball 70.

[0035] The ball seat 71 is a ring-shaped member that sandwiches the ball 70 with an appropriate interference, and is made of an elastic material.

[0036] In the valve 1 of this embodiment, which uses a ball valve, a floating structure or a trunnion structure is used as a method of supporting the ball 70 depending on the situation.

[0037] Next, the operation of the valve 1 when in use will be described.

[0038] First, the stem 20 is enclosed in the outer cylinder portion 30, and one end of the shaft portion 21 is connected to the ball 70. The other end of the shaft portion 21 (shank portion 24) is connected to the handle portion 40.

[0039] At this time, when the fluid can pass through the through-hole of ball 70 (i.e., when valve 1 is open) and when the fluid cannot pass through the through-hole of ball 70 (i.e., when valve 1 is closed), dome portion 26 and tapered portion 31 of outer cylinder portion 30 are in metal contact (line contact). At this time, even if a foreign object passes through the metal contact portion, further movement of the foreign object can be prevented at the point of contact between elastic body 23 and outer cylinder portion 30.

[0040] In a state where fluid cannot pass through the through hole of ball 70 (i.e., when valve 1 is fully open) and in a state where fluid can pass through the through hole of ball 70 (i.e., when valve 1 is open), even when handle portion 40 is rotated, a biasing force is exerted from spring portion 22 to outer tube portion 30, so the sealing function is maintained constant at the contact point between tapered portion 31 and dome portion 26.

[0041] At the same time, due to elastic deformation of the elastic body 23 placed in the first recess 27 formed on the circumferential surface of the large diameter portion 25, a sealing function is also achieved at the contact point between the elastic body 23 and the outer cylindrical portion 30.

[0042] Even if the handle portion 40 is repeatedly rotated, the sealing function can be maintained while the fluid is appropriately controlled.

[0043] The sealing mechanism 10 according to the present embodiment, configured as described above, includes a shaft portion 21 having a shaft portion 24, a large-diameter portion 25 having a diameter larger than that of the shaft portion 24, and a dome portion 26 provided on one end of the large-diameter portion 25 and on the circumferential surface of the shaft portion 24; a spring portion 22 disposed at the other end of the large-diameter portion 25; an elastic body 23 placed in a first recess 27 formed on the circumferential surface of the large-diameter portion 25; and an outer tube portion 30 that encompasses the shaft portion 21, the spring portion 22, and the elastic body 23, has a tapered portion 31 formed along the curved surface of the dome portion 26, and is in contact with at least the large-diameter portion 25 and the dome portion 26 of the shaft portion 21. More specifically, in the prior art, a relatively large space is filled with various components, resulting in a large number of parts. Furthermore, because the sealing function is expected to be achieved by elastic deformation of the packing material, a design that takes elastic deformation into account is required, which complicates the design of manufacturing tolerances. In contrast, the sealing mechanism 10 of the present embodiment has the above-described configuration, and thereby exerts a sealing function by concentrating the spring force at the contact point between the dome portion 26 and the tapered portion 31 and continuing to exert the spring force from the spring portion 22. Therefore, the sealing function can be exerted due to the shape of the sealing mechanism 10, and the sealing function can be exerted more efficiently without considering the elasticity of the components.

[0044] Furthermore, in the seal mechanism 10 of the present embodiment, as described above, the taper angle of the tapered portion 31 may be an angle in the range of 30° or more and less than 180°. In this case, while still providing a sealing function, it is possible to avoid interference with smooth rotation due to members getting caught between each other when the shaft portion 21 rotates.

[0045] Furthermore, as described above, the seal mechanism 10 of this embodiment may include the bearing 50 placed on the spring portion 22 and the fixing member 60 that fixes the bearing 50. In this case, a constant biasing force can be efficiently transmitted to the dome portion 26 and the tapered portion 31 while ensuring that the shaft portion 21 is fixed.

[0046] In addition, in the seal mechanism 10 of this embodiment, as described above, the elastic body 23 may be an O-ring. In this case, the elastic body 23 can be effectively applied to the first recess 27 formed in the large diameter portion 25.

[0047] Furthermore, in the seal mechanism 10 of this embodiment, as described above, the other end surface of the large diameter portion 25 may extend in the radial direction relative to the longitudinal axis of the shaft portion 21. In this case, the surface direction of the other end surface of the large diameter portion 25 is perpendicular to the biasing direction, so that the biasing force can be transmitted to the dome portion 26 and the tapered portion 31 more efficiently.

[0048] Furthermore, in the seal mechanism 10 of the present embodiment, as described above, the inner circumferential surface of the outer tubular portion 30 may be in contact with the elastic body 23. In this case, the sealing function can be exerted also at the contact points between the elastic body 23 and the outer tubular portion 30 in the vicinity of the dome portion 26 and the tapered portion 31, and the sealing function can be exerted more effectively.

[0049] Furthermore, the valve 1 according to this embodiment includes the above-described seal mechanism 10. In this case, it is possible to realize the valve 1 that exhibits the sealing function provided by the above-described seal mechanism 10.

[0050] The sealing mechanism 10 according to the present embodiment is not limited to the above-described embodiment, and various modifications can be made thereto.

[0051] In the present embodiment, the seal mechanism 10 is applied to the valve 1, but the application is not limited to this. For example, the seal mechanism 10 may be applied to a rotary joint 100.

[0052] Rotary joint 100 includes seal mechanism 10. As shown in FIG. 2 , seal mechanism 10 applied to rotary joint 100 uses a spring as spring portion 22. One end of spring portion 22 (on the dome portion 26 side) is mounted on a member (bearing 50) that is mounted on the other end surface of large diameter portion 25, and can be biased toward the other end via bearing 50. A bearing 50 is also mounted on the other end of spring portion 22. As a result, spring portion 22 is sandwiched between the two bearings 50.

[0053] Furthermore, in the present embodiment, the seal mechanism 10 has been described as being applied to a ball valve and rotary joint 100, but the seal mechanism 10 can also be applied to other valve mechanisms and joints as long as it is applicable.

Claims

1. A sealing mechanism comprising: a shaft portion having a shaft portion, a large diameter portion larger in diameter than the shaft portion, and a dome portion provided on one end of the large diameter portion and on the circumferential surface of the shaft portion; a spring portion located at the other end of the large diameter portion; an elastic body placed in a recess formed on the circumferential surface of the large diameter portion; and an outer tubular portion that encompasses the shaft portion, the spring portion, and the elastic body, has a tapered portion formed along the curved surface of the dome portion, and is in contact with at least the large diameter portion and the dome portion of the shaft portion.

2. The sealing mechanism according to claim 1, wherein the taper angle of the tapered portion is in the range of 30° or more and less than 180°.

3. The sealing mechanism according to claim 1, comprising: a bearing placed on the spring portion; and a fixing member that fixes the bearing.

4. The seal mechanism according to claim 1, wherein the elastic body is an O-ring.

5. The seal mechanism according to claim 1, wherein the other end face of the large diameter portion extends in a radial direction relative to the longitudinal axis of the shaft portion.

6. The sealing mechanism according to claim 1, wherein the inner peripheral surface of the outer cylindrical portion is in contact with the elastic body.

7. A valve equipped with the sealing mechanism according to claim 1.

8. A rotary joint equipped with the seal mechanism according to claim 1.

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